It's part my own detective work and some of the stuff I've read at HongKong and Japanese sites where ppl have opened their Master Cases.
I've been keeping track of all of the Lograys and Ion Rifle Jawas I see on eBay, Japan eBay (bidders), and both of the yahoo auction sites for Japan & Hong Kong.
Almost all the auctions state that with the Master Cases you will always end up with either Logray or Jawa, meaning that they are 1:96 if evenly split, but I keep seeing Logray much more than the Jawa being pulled.
No hard evidence yet (too early), but lots of circumstantial evidence pointing to a 1:192 Jawa and 1:48 Logray instead of both of them being 1:96.
Jeff